KR101444976B1 - Method For Preparing α,β-unsaturated Aldehyde - Google Patents

Abstract

More particularly, the present invention relates to a process for producing an alpha, beta -unsaturated aldehyde using an aldol-condensation reaction, wherein the aldol condensation reaction is carried out in the presence of aldehyde and 0.2 to 2.0% Wherein the weight ratio of the aldehyde and the NaOH aqueous solution (aldehyde: NaOH aqueous solution) is in the range of 1.0: 0.6 to 1.0: 1.7, .
According to the present invention, there is an effect of providing a process for producing an alpha, beta -unsaturated aldehyde having a small side reaction and excellent selectivity of a product.

Description

Method for preparing alpha, beta-unsaturated aldehydes {Method For Preparing alpha, beta-unsaturated Aldehyde}

More particularly, the present invention relates to a process for producing an alpha, beta -unsaturated aldehyde having a small side reaction and an excellent selectivity of a product.

The aldol condensation reaction is a very important reaction in industry. The α, β-unsaturated carbonyl compound produced at this time is used as a starting material or an intermediate for the synthesis of numerous organic compounds due to the specific reactivity.

In addition, the alpha, beta -unsaturated aldehydes are hydrogenated and converted to saturated aldehydes which can be oxidized to carboxylic acids, which are used as raw materials for lubricating oils, desiccants, peresters or stabilizers for plastics.

Further, complete hydrogenation of the alpha, beta -unsaturated aldehydes results in the formation of primary, saturated alcohols used in the preparation of detergents and plasticizers or as solvents.

The aldol condensation reaction is catalyzed by an acid or a base, and inorganic bases such as NaOH are used in industrial processes.

German Patent No. 3,530,839 discloses that n-butyraldehyde is reacted at a retention time of 0.2 to 5 minutes in a flow tube at 100 to 170 DEG C under a superatmospheric pressure using an aqueous solution of sodium hydroxide at a concentration of 0.5 to 5 wt% Deg.] C, separating the reaction product into a catalyst aqueous solution and an organic phase, discharging a portion of the catalyst aqueous solution to remove it, and replacing the catalyst solution with a new catalyst solution, recirculating the catalyst solution into the flow tube, and obtaining 2-ethylhex- - condensation reaction.

However, since a large amount of the catalyst is consumed by discharging and removing a part of the catalyst aqueous solution, and the discharged catalyst aqueous solution contains an organic compound, there is a problem of additional cost because it needs to be post-treated or treated in the effluent treatment apparatus.

Also, EP 634,994 discloses a process for the preparation of a catalyst comprising the steps of: a) injecting a starting aldehyde and a catalyst aqueous solution into a stirred reactor under non-adiabatic conditions; b) introducing the reaction mixture obtained from the stirred reactor into the middle part of the distillation column; c) separating the organic layer (starting material and water vapor) on the distillation column and the aqueous layer (catalyst aqueous solution, product and byproduct) on the bottom; d) discharging a portion of the aqueous layer; e) recirculating the organic layer to the reactor; f) obtaining an aqueous layer below the distillation column as a bottom product; g) cooling the bottom product; h) separating the cooled bottom product into an upper organic phase containing the product, a high molecular weight byproduct and a small amount of the catalyst solution, and a lower catalyst aqueous solution containing the carboxylic acid formed as a by-product of the salt form; i) recirculating the catalyst aqueous solution to the reactor; And j) discharging the organic phase on top of the aldol condensation reaction.

However, energy is required for the distillation of the reaction mixture, a cooling medium is required for cooling the lower product, and the reaction mixture present on the catalyst in the distillation step is thermally stressed to produce by-products by the cannizzaro reaction And the final crude product is separated from the apparatus without being cleaned and still contains a small amount of catalyst to deteriorate the quality of the product during the storage period and when it is used for chemical synthesis such as hydrogenation reaction It can cause serious problems.

Therefore, it is urgent to develop a process for producing an alpha, beta -unsaturated aldehyde having a low side reaction and high selectivity for a product, which is excellent in efficiency and economical efficiency.

In order to solve the problems of the prior art as described above, it is an object of the present invention to provide a process for producing an alpha, beta -unsaturated aldehyde having a small side reaction and excellent selectivity of products.

These and other objects of the present invention can be achieved by the present invention described below.

In order to achieve the above object, the present invention provides a process for producing an alpha, beta -unsaturated aldehyde using an aldol-condensation reaction, wherein the aldol condensation reaction is carried out at 90 to 130 ° C , Wherein the weight ratio of the aldehyde and the NaOH aqueous solution (aldehyde: NaOH aqueous solution) is 1.0: 0.6 to 1.0: 1.7.

As described above, according to the present invention, there is an effect of providing a process for producing an alpha, beta -unsaturated aldehyde having a small side reaction and an excellent selectivity of a product.

1 is a schematic view showing an example of a reaction apparatus to which the process for producing an alpha, beta -unsaturated aldehyde according to the present invention is applied.

Hereinafter, the present invention will be described in detail.

The process for producing an alpha, beta -unsaturated aldehyde according to the present invention is a process for producing an alpha, beta -unsaturated aldehyde using an aldol condensation reaction, wherein the aldol condensation reaction is carried out at a temperature of 90 - (Aldehyde: NaOH aqueous solution) of the aldehyde and the NaOH aqueous solution is 1.0: 0.6 to 1.0: 1.7.

The aldol condensation reaction may be preferably a symmetrical aldol condensation reaction. Specific reaction examples are shown in FIG.

[Figure 1]

The aldehyde is preferably n-aldehyde, more preferably N-butyraldehyde.

The NaOH aqueous solution may be a 0.2 to 2.0% NaOH aqueous solution, preferably 0.3 to 1.8% NaOH aqueous solution, more preferably 0.8 to 1.0% NaOH aqueous solution. Within this range, 2-ethylhexenal ) Is high.

The% NaOH aqueous solution means a weight% NaOH aqueous solution.

The weight ratio (aldehyde: NaOH aqueous solution) of the aldehyde and the NaOH aqueous solution may be 1.0: 0.6 to 1.0: 1.7, preferably 1.0: 1.0 to 1.0: 1.3, and the yield of 2-ethylhexenal Is high.

The aldol condensation reaction is preferably carried out at 90 to 130 ° C, more preferably 100 to 110 ° C. In this range, the amount of unreacted n-butane is not increased, and the number of carbon atoms is 12 And the yield of 2-ethylhexenal is increased.

The aldol condensation reaction may be carried out at a pressure of 1 to 10 bar, preferably at a pressure of 2 to 4 bar. Within this range, the reactant does not vaporize at a pressure higher than the vapor pressure of n-butanal, Effective for aldol reactions, high pressures exceeding 4 bar are unnecessary for aldol reactions.

The aldol condensation reaction may be carried out for 0.1 to 1.0 hour, preferably for 0.2 to 0.5 hour. While maintaining the unreacted n-butane egg at a certain level within this range, It is possible to reduce the high-boiling point compound, thereby increasing the yield of 2-ethylhexenal.

The reactor used in the aldol condensation reaction is preferably a continuous reactor (CSTR). In this case, the mixing of the reactant n-butanol and the aqueous solution containing the catalyst is facilitated, the mass transfer of n-butanal is expected to occur, and the reaction heat of the aldol reaction can be easily controlled.

1 shows a concrete example of a reaction apparatus 100 to which the method for producing an alpha, beta -unsaturated aldehyde of the present invention is applied. However, reaction temperature control means, reaction pressure control means and the like, which are well known to those skilled in the art, have been omitted.

Aldehyde and an aqueous NaOH solution, which are starting materials, are introduced into the aldol condensation reactor (10) through a reaction material feed pipe (1), subjected to aldol condensation reaction at a predetermined temperature, pressure and time, 2 to the distillation column 20. [

The aldehyde with low boiling point and some alpha, beta -unsaturated aldehyde and the like are moved to the aldehyde / product separator 30 via the upper pipe 3 and the aldehyde is recovered through the recovery pipe 4 ), And the product?,? - unsaturated aldehyde is obtained through the discharge pipe (7).

On the other hand, in the product mixture flowing into the distillation column 20, the NaOH aqueous solution and the alpha, beta -unsaturated aldehyde, etc. having a high boiling point are transferred to the catalyst solution / product separator 40 via the bottom pipe 5, Is recycled to the aldol condensation reactor (10) through the recovery pipe (6), and the product?,? - unsaturated aldehyde is obtained through the discharge pipe (8).

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

[Example]

Example 1

10 kg of the reactant n-butanol (purity of 99.8% or more, LG Chemical) and 1.8% NaOH aqueous solution were charged in the respective raw material tanks. In a CSTR reactor having a capacity of 1 L, 1.8 g NaOH aqueous solution and 2-ethylhexenal were injected in the order of 330 g each. Thereafter, the CSTR reactor was pressurized with nitrogen to keep the reactor at 2 bar, and the temperature of the reactor was raised to 130 ° C. while stirring the stirrer of the CSTR reactor at 500 rpm. When the internal temperature of the reactor was stabilized at a reaction temperature of about +/- 1.0 DEG C, the stirring speed was increased to 1500 rpm. Then, the reactant n-butane and NaOH aqueous solution were supplied to the CSTR reactor at a rate of 1.28 kg / hr and 1.04 kg / hr, respectively, using a diaphragm pump, and the reactant The product was recovered through the level control valve. The product was sampled every hour after the reaction was supplied. The sample was taken about 30 g. After sampling, the water layer and the organic layer were separated using a separatory funnel for 1 hour. The separated water layer was washed with 0.1N HCl NaOH concentration was measured by titration and the organic layer was analyzed by gas chromatography. At this time, the components were analyzed by the methods described in the following test examples, and the results are shown in Table 1 below.

Example 2

The procedure of Example 1 was repeated, except that the reaction temperature was changed to 110 ° C.

Example 3

The procedure of Example 1 was repeated except that the reaction temperature was 90 ° C in Example 1.

Example 4

The procedure of Example 1 was repeated except that 1.4% NaOH aqueous solution was used in Example 1.

Example 5

The procedure of Example 1 was repeated except that 1.4% NaOH aqueous solution was used in Example 1 and the reaction temperature was 110 ° C.

Example 6

The procedure of Example 1 was repeated except that 1.4% NaOH aqueous solution was used in Example 1 and the reaction temperature was 90 ° C.

Example 7

The procedure of Example 1 was repeated except that 1.2% NaOH aqueous solution was used in Example 1.

Example 8

Example 1 was carried out in the same manner as in Example 1, except that 1.2% NaOH aqueous solution was used and the reaction temperature was 110 ° C.

Example 9

The procedure of Example 1 was repeated except that 1.2% NaOH aqueous solution was used in Example 1 and the reaction temperature was 90 ° C.

Example 10

The procedure of Example 1 was repeated except that 0.8% NaOH aqueous solution was used in Example 1.

Example 11

The procedure of Example 1 was repeated except that 0.8% aqueous NaOH solution was used in Example 1 and the reaction temperature was 110 ° C.

Example 12

The procedure of Example 1 was repeated except that 0.8% NaOH aqueous solution was used in Example 1 and the reaction temperature was 90 ° C.

Example 13

The procedure of Example 1 was repeated except that 0.4% NaOH aqueous solution was used in Example 1.

Example 14

The procedure of Example 1 was repeated except that 0.4% NaOH aqueous solution was used in Example 1 and the reaction temperature was 110 ° C.

Example 15

The same procedure as in Example 1 was carried out except that 0.4% NaOH aqueous solution was used in Example 1 and the reaction temperature was 90 ° C.

Example 16

The procedure of Example 1 was repeated except that 0.2% NaOH aqueous solution was used in Example 1.

Example 17

The procedure of Example 1 was repeated except that 0.2% NaOH aqueous solution was used in Example 1 and the reaction temperature was 110 ° C.

Example 18

The procedure of Example 1 was repeated except that 0.2% NaOH aqueous solution was used in Example 1 and the reaction temperature was 90 ° C.

Comparative Example 1

The same procedure as in Example 1 was carried out except that 0.1% NaOH aqueous solution was used in Example 1 above.

Comparative Example 2

The procedure of Example 1 was repeated except that the reaction temperature was 150 ° C in Example 1.

Comparative Example 3

The reaction was carried out in the same manner as in Example 1 except that the reaction temperature in Example 1 was 80 占 폚.

Example 19

A reaction rate of 1.02 kg / hr (weight ratio of aldehyde and NaOH aqueous solution (aldehyde: NaOH aqueous solution) = 1.28: 1.02, NaOH Aqueous solution / aldehyde = 0.8) was used as the catalyst.

Example 20

Example 1 was repeated except that the feeding rate of the aqueous NaOH solution was changed to 1.28 kg / hr (the weight ratio of aldehyde and NaOH aqueous solution (aldehyde: NaOH aqueous solution) = 1.28: 1.28, NaOH aqueous solution / aldehyde = 1.0) . ≪ / RTI >

Example 21

The procedure of Example 20 was repeated except that the feed rate of the aqueous NaOH solution was changed to 1.53 kg / hr (weight ratio of aldehyde and NaOH aqueous solution (aldehyde: NaOH aqueous solution) = 1.28: 1.53, aqueous NaOH solution / . ≪ / RTI >

Comparative Example 4

The procedure of Example 20 was repeated except that the feed rate of the aqueous NaOH solution was changed to 0.64 kg / hr (the weight ratio of aldehyde to NaOH aqueous solution (aldehyde: NaOH aqueous solution) = 1.28: 0.64, NaOH aqueous solution / aldehyde = 0.5) . ≪ / RTI >

Comparative Example 5

The procedure of Example 20 was repeated except that the feeding rate of the NaOH aqueous solution was changed to 2.56 kg / hr (weight ratio of aldehyde to NaOH aqueous solution (aldehyde: NaOH aqueous solution) = 1.28: 2.56, NaOH aqueous solution / aldehyde = 2.0) . ≪ / RTI >

[Test Example]

The compositions and contents of the?,? - unsaturated aldehydes prepared in the above Examples were measured and analyzed by gas chromatography mass spectrometry (HP 5890, Hewlett-Packard Company). The conversion of n-butanal, the selectivity of 2-ehtylhexenal and the yield were calculated from the measured composition by using the following equations (1) to (3), and the results are shown in Table 1 below.

As shown in Table 1 above, the production methods of the?,? - unsaturated aldehydes (Examples 1 to 21) according to the present invention are different from those of the present invention in that the concentration of NaOH aqueous solution, reaction temperature and content ratio of aldehyde and NaOH aqueous solution Butanal conversion and the selectivity and yield of 2-ethylhexenal were all higher than those of Comparative Example 1 (Comparative Examples 1 to 5).

For reference, when the NaOH aqueous solution concentration was outside the range of the present invention (Comparative Example 1), the conversion of n-butanol and the yield of 2-ethylhexenal were significantly lowered. When the reaction temperature was outside the range of the present invention 2 and 3), the selectivity and yield of 2-ethylhexenal were significantly lowered or the n-butanal conversion and the yield of 2-ethylhexenal were significantly lowered. When the weight ratio of the aldehyde and NaOH aqueous solution was out of the range of the present invention Comparative Examples 4 and 5) It was confirmed that the conversion of n-butanol and the yield of 2-ethylhexenal were remarkably lowered, and the selectivity and yield of 2-ethylhexenal were significantly lowered.

1: Reaction raw material supply pipe 2: Reaction product mixture discharge pipe
3: Top piping 4: Aldehyde recovery piping
5: lower pipe 6: catalyst solution recovery pipe
7, 8: Product discharge piping
10: aldol condensation reactor 20: distillation column
30: aldehyde / product separator 40: catalyst solution / product separator

Claims (7)

In the process for producing an alpha, beta -unsaturated aldehyde by an aldol condensation reaction, the aldol condensation reaction is carried out at 90 to 130 ° C including an aldehyde and an aqueous solution of 0.2 to 2.0 wt% NaOH,
The weight ratio (aldehyde: NaOH aqueous solution) of the aldehyde and the NaOH aqueous solution is 1.0: 0.6 to 1.0: 1.7
A process for producing an alpha, beta-unsaturated aldehyde. The method according to claim 1,
The aldol condensation reaction is a symmetrical aldol condensation reaction.
A process for producing an alpha, beta-unsaturated aldehyde. The method according to claim 1,
Characterized in that the aldehyde is n-aldehyde
A process for producing an alpha, beta-unsaturated aldehyde. The method according to claim 1,
The NaOH aqueous solution is a 0.8 to 1.0 wt% NaOH aqueous solution
A process for producing an alpha, beta-unsaturated aldehyde. The method according to claim 1,
Wherein the weight ratio of the aldehyde to the NaOH aqueous solution is 1.0: 1.0 to 1.0: 1.3
A process for producing an alpha, beta-unsaturated aldehyde. The method according to claim 1,
The aldol condensation reaction is carried out at a pressure of 1 to 10 bar.
A process for producing an alpha, beta-unsaturated aldehyde. The method according to claim 1,
The aldol condensation reaction is carried out by a continuous-type reactor (CSTR)
A process for producing an alpha, beta-unsaturated aldehyde.

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